Connecting an ISDN PBX for DDI Lines

You can operate an ISDN telephone system for DDI lines on the "FON S0" jack of the FRITZ!Box.

Connecting and Configuring an ISDN PBX

Overview

You can operate a telephone system for ISDN DDI lines on the FRITZ!Box. However, AVM cannot guarantee smooth operation of this kind of telephone system. The FRITZ!Box's jack for ISDN devices (FON S0) of the FRITZ!Box was developed for telephones and other devices designed for point-to-point ISDN lines.

Point-to-point lines are common in the private sphere, whereas DDI interfaces are special ISDN lines for businesses.

Rules

  • If you connect a telephone system for DDI lines on the "FON S0" jack, you cannot connect any other ISDN devices to the FRITZ!Box.

Requirements

  • Your internet telephone numbers are set up under "Telephony / Telephone Numbers" in the user interface.

Instructions: Connecting a PBX and Restarting the FRITZ!Box

Connect the PBX and restart the FRITZ!Box. During restart, the "FON S0" jack will be switched to "DDI line" operating mode.

  1. Connect the PBX to the "FON S0" jack.
  2. Select "System / Backup / Restart" in the user interface.
  3. Click on "Restart".

Instructions: Configuring a PBX in the FRITZ!Box

  1. In the user interface, select "Telephony / Telephony Devices".
  2. Click "Configure New Device".
  3. Enable the option "ISDN PBX".
  4. Click "Next" and follow the wizard's instructions.

Configuring the Extensions of your PBX

Once you have set up the PBX in the FRITZ!Box, you can assign telephone numbers to the extensions of the PBX. In so doing, please note:

  • Enter in the PBX only telephones that are configured in the FRITZ!Box. Exception: Extension numbers of an SIP DDI line do not have to be entered in the FRITZ!Box.
  • Enter the internet telephone numbers in the PBX exactly as they are displayed under "Telephony / Telephone Numbers" in the FRITZ!Box user interface.

Troubleshooting

Overview

If problems arise when establishing connections on the PBX, you can disable the energy-saving mode of the FRITZ!Box. One of the functions reduced during energy-saving operation is the power to the "FON S0" jack. This can lead to malfunctions with some ISDN devices.

Requirements

  • There is a telephone connected to the FRITZ!Box with which you can dial * and # and send keypad shortcuts (sequences of characters and numerals like *121#). On many telephones, you can configure this function in the menu "Operation at a PBX > Dialing options > Dial * and #".

Instructions: Disabling Energy-Saving Mode in the FRITZ!Box

  1. Enter the following keypad sequence on your telephone: #966*1*
  2. Press the call key (lift the receiver).
  3. Hang up again after about 3 seconds.

You can enable energy-saving mode again by entering #966*0*.